1) How many vehicle “Underpasses” exists in TFL's area? 2) How many vehicle “Tunnels” exists in TFL's area? 3) Who is responsible for the operations and maintenance of vehicle Underpasses and Tunnels in TFL's area? 4) What is the age of the oldest “Underpass”? 5) What is the age of the newest “Underpass”? 6) Drainage design rainfall return period for “Underpass”? 7) Drainage design rainfall return period for “Tunnel”? 8) Past flooding occurrences of “Underpasses” and the cause (i.e. drainage inadequate, rain exceeding design return period)? 9) Contingency measures to deal with severe weather, i.e. rain event? (Most likely a Contingency Plan or Emergency Plan) 10) Is “Underpass” / “Tunnel” closure a standard contingency measure in case of expected / actual flooding may occur? 11) What is included in the Business as Usual (Standard) Maintenance Plan for “Underpass”/“Tunnel” drainage systems? 12) What is included in the Rainy Season Readiness Maintenance Plan for “Underpass”/“Tunnel” drainage systems?

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Our Ref:          FOI-2983-1718

Thank you for your request received on 16 January 2018 asking for information about underpasses on the TfL Road Network (TLRN).

Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm we hold some of the information you require. You asked:

1. How many vehicle “Underpasses” exist in TFL's area?

On the TLRN there are x67 underpasses/bridges crossing roads below ground level which are maintained by TfL. Some of these, particularly on the NCR (North Circular Road), are grouped closely together, on the same sag curve and share fewer pump stations between them.

2. How many vehicle “Tunnels” exist in TFL's area?
There are 12 tunnel structures maintained by TfL.

3. Who is responsible for the operations and maintenance of vehicle underpasses and tunnels in TfL’s area?

TfL is responsible and the underpasses and tunnels are maintained by contracted companies under TfL’s supervision.

4. What is the age of the oldest “Underpass”?

The oldest underpass was constructed in 1830 but the oldest underpass where there is a TfL road underneath was built in 1960 and was itself an extension of an existing junction.

5. What is the age of the newest “Underpass”?

The newest underpass is currently under construction where a Victorian structure is being replaced. The most recent where a TLRN road is on the bottom was built in 2001 and was itself an extension of an existing junction.

6) Drainage design rainfall return period for “Underpass”?
7) Drainage design rainfall return period for “Tunnel”?

Unfortunately, to provide the information you have requested in Q6 and Q7 of your request would exceed the ‘appropriate limit’ of £450 set by the Freedom of Information (Appropriate Limit and Fees) Regulations 2004.

Under section 12 of the FOI Act, we are not obliged to comply with a request if we estimate that the cost of determining whether we hold the information, locating and retrieving it and extracting it from other information would exceed the appropriate limit. This is calculated at £25 per hour for every hour spent on the activities described.

We have estimated that it would cost above the limit to provide a response to your current request. This is because it is estimated that it would take over 18 working hours to retrieve and compile the information you have requested. This information is not centrally recorded and would need to be identified and collated from several sources.

To help bring the cost of responding to your request within the £450 limit, you may wish to consider narrowing its scope so that we can more easily locate, retrieve and extract the information you are seeking. If you want to refine your request or make a Freedom of Information Act request in future, please bear in mind that the Freedom of Information Act allows you to request recorded information held by Transport for London. You should identify the information that you want as clearly and concisely as you can, specifying the types of document that you are looking for. You might also consider limiting your request to a particular period of time, geographical area or specific departments of TfL.

8. Past flooding occurrences of “Underpasses” and the cause (i.e. drainage inadequate, rain exceeding design return period)?

We do not keep records of historical events of flooding for individual structures.

9. Contingency measures to deal with severe weather, i.e. rain event? (Most likely a Contingency Plan or Emergency Plan)

The tunnels have a drainage system, if however the severity of the weather presents a greater capacity that can be managed the tunnel would be closed until it is resolved / managed as appropriate before reopening

10. Is “Underpass” / “Tunnel” closure a standard contingency measure in case of expected / actual flooding may occur?

This is not a ‘standard contingency measure’ as it is dependent on a high water alarm (in the sump of the tunnel bore).

11. What is included in the Business as Usual (Standard) Maintenance Plan for “Underpass”/“Tunnel” drainage systems?

Drainage systems are jetted and cleaned in line with the individual underpass or Tunnel closure programme which varies across the network due to need and road space availability. In conjunction with this mechanical & electrical drainage components are serviced every 6 months but are monitored continuously via telemetry.

12. What is included in the Rainy Season Readiness Maintenance Plan for “Underpass”/“Tunnel” drainage systems?

In the UK we do not have a rainy season as such but can experience heavy rainfall during any season. We have a Severe Weather Desk which is initiated when there are severe warnings from the Met Office.

If this is not the information you are looking for please feel free to contact me.

Please see the attached information sheet for details of your right to appeal.

Yours sincerely

Gemma Jacob
FOI Case Officer
FOI Case Management Team
General Counsel
Transport for London

[email protected]

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